// https://leetcode.cn/problems/climbing-stairs/submissions/544649690/
class Solution {
public:
    int climbStairs(int n) {
        long long dp[64] = {0};
        dp[0] = dp[1] = 1;
        dp[2] = 2;
        for (int i = 2; i <= n; i++) {
            dp[i] = dp[i-1]+dp[i-2];
        }
        return dp[n];
    }
};